1992/1001/port/fault.c (diff list | history)

port/fault.c on 1990/0227
1990/0227		#include "u.h"
1992/0321		#include "../port/lib.h"
1990/0227		#include "mem.h" #include "dat.h" #include "fns.h"
1992/0111		#include "../port/error.h"
1990/0227
1992/0114		void faulterror(char*);
1991/1105
1990/1212		int fault(ulong addr, int read)
1990/0227		{
1991/0705		Segment *s;
1991/0926		char *sps;
1990/0227
1991/0926		sps = u->p->psstate; u->p->psstate = "Fault";
1992/0602		spllo();
1991/0926
1991/0427		m->pfault++;
1991/1109		for(;;) { s = seg(u->p, addr, 1); if(s == 0) { u->p->psstate = sps; return -1; }
1991/0705
1991/1109		if(!read && (s->type&SG_RONLY)) { qunlock(&s->lk); u->p->psstate = sps; return -1; } if(fixfault(s, addr, read, 1) == 0) break;
1990/0227		}
1991/0705
1991/1109		u->p->psstate = sps; return 0; } int fixfault(Segment *s, ulong addr, int read, int doputmmu) { ulong mmuphys=0, soff;
1992/0805		Page **pg, *lkp, *new;
1991/1122		Pte **p, *etp;
1991/1109		int type;
1991/0705		addr &= ~(BY2PG-1); soff = addr-s->base; p = &s->map[soff/PTEMAPMEM]; if(*p == 0) *p = ptealloc();
1991/1122		etp = *p; pg = &etp->pages[(soff&(PTEMAPMEM-1))/BY2PG];
1991/0705		type = s->type&SG_TYPE;
1991/1122		if(pg < etp->first) etp->first = pg; if(pg > etp->last) etp->last = pg;
1991/0705		switch(type) {
1992/0307		default: panic("fault");
1992/0319		break;
1992/0307
1991/0705		case SG_TEXT:
1992/0430		if(pagedout(*pg)) /* Demand load */
1991/0705		pio(s, addr, soff, pg); mmuphys = PPN((*pg)->pa) | PTERONLY|PTEVALID; (*pg)->modref = PG_REF; break;
1992/0302
1992/0430		case SG_SHDATA: /* Shared data */
1992/0307		if(pagedout(*pg)) pio(s, addr, soff, pg); goto done;
1991/0705		case SG_BSS:
1992/0430		case SG_SHARED: /* Zero fill on demand */
1991/0705		case SG_STACK:
1992/0103		if(*pg == 0) {
1992/0805		new = newpage(1, &s, addr);
1992/0302		if(s == 0)
1991/1109		return -1;
1992/0307
1991/0705		*pg = new;
1990/0227		}
1991/1113		/* NO break */
1992/0302
1992/0430		case SG_DATA: /* Demand load/pagein/copy on write */
1991/0705		if(pagedout(*pg)) pio(s, addr, soff, pg);
1992/0307
1991/0705		if(type == SG_SHARED) goto done;
1991/0607
1992/0629		if(read && conf.copymode == 0) {
1991/0705		mmuphys = PPN((*pg)->pa) | PTERONLY|PTEVALID; (*pg)->modref |= PG_REF; break;
1990/0227		}
1991/0705		lkp = *pg;
1992/0625		lock(lkp);
1991/0705		if(lkp->ref > 1) {
1992/0625		unlock(lkp);
1992/0805		new = newpage(0, &s, addr);
1992/0302		if(s == 0)
1991/1109		return -1;
1991/0705		*pg = new; copypage(lkp, *pg); putpage(lkp);
1990/0227		}
1991/0705		else { /* put a duplicate of a text page back onto the free list */ if(lkp->image) duppage(lkp);
1992/0625		unlock(lkp);
1990/0227		}
1991/0705		done: mmuphys = PPN((*pg)->pa) | PTEWRITE|PTEVALID; (*pg)->modref = PG_MOD|PG_REF; break;
1992/0302
1991/0705		case SG_PHYSICAL: if(*pg == 0) *pg = (*s->pgalloc)(addr);
1991/0606
1991/0705		mmuphys = PPN((*pg)->pa) | PTEWRITE|PTEUNCACHED|PTEVALID; (*pg)->modref = PG_MOD|PG_REF; break;
1990/0227		}
1991/0608
1991/1110		if(s->flushme) memset((*pg)->cachectl, PG_TXTFLUSH, sizeof(new->cachectl));
1991/0705		qunlock(&s->lk);
1991/0719
1991/1109		if(doputmmu) putmmu(addr, mmuphys, *pg);
1991/0705		return 0; } void pio(Segment *s, ulong addr, ulong soff, Page **p) { Page *new; KMap *k; Chan *c; int n, ask; char *kaddr; ulong daddr; Page *loadrec; loadrec = *p; if(loadrec == 0) {
1991/0709		daddr = s->fstart+soff; /* Compute disc address */
1991/0705		new = lookpage(s->image, daddr);
1990/0227		}
1991/0705		else { daddr = swapaddr(loadrec); new = lookpage(&swapimage, daddr); if(new) putswap(loadrec); }
1991/0607
1991/0709		if(new) { /* Page found from cache */
1991/0705		*p = new; return; }
1991/0607
1991/0705		qunlock(&s->lk); new = newpage(0, 0, addr); k = kmap(new); kaddr = (char*)VA(k); if(loadrec == 0) { /* This is demand load */ c = s->image->c;
1991/0906		while(waserror()) {
1992/0111		if(strcmp(u->error, Eintr) == 0)
1991/0906		continue;
1991/0705		kunmap(k); putpage(new);
1992/0114		faulterror("sys: demand load I/O error");
1991/0705		} ask = s->flen-soff; if(ask > BY2PG) ask = BY2PG;
1992/0319
1991/0705		n = (*devtab[c->type].read)(c, kaddr, ask, daddr); if(n != ask) error(Eioload); if(ask < BY2PG) memset(kaddr+ask, 0, BY2PG-ask); poperror(); kunmap(k); qlock(&s->lk); if(*p == 0) { /* Someone may have got there first */ new->daddr = daddr; cachepage(new, s->image); *p = new; } else putpage(new); } else { /* This is paged out */ c = swapimage.c; if(waserror()) { kunmap(k); putpage(new); qlock(&s->lk); qunlock(&s->lk);
1992/0114		faulterror("sys: page in I/O error");
1991/0705		} n = (*devtab[c->type].read)(c, kaddr, BY2PG, daddr); if(n != BY2PG) error(Eioload); poperror(); kunmap(k); qlock(&s->lk); if(pagedout(*p)) { new->daddr = daddr; cachepage(new, &swapimage); putswap(*p); *p = new; } else putpage(new); }
1991/1105		} void
1992/0114		faulterror(char *s)
1991/1105		{
1992/1001		print("faulterror %s\n", s);
1991/1105		if(u->nerrlab) { postnote(u->p, 1, s, NDebug);
1992/0114		error(s);
1991/1105		} pexit(s, 0);
1990/0227		} /* * Called only in a system call */
1992/0616		int okaddr(ulong addr, ulong len, int write)
1990/0227		{
1991/0705		Segment *s;
1990/0227
1991/0705		if((long)len >= 0) { for(;;) { s = seg(u->p, addr, 0); if(s == 0 || (write && (s->type&SG_RONLY))) break; if(addr+len > s->top) { len -= s->top - addr; addr = s->top; continue; }
1992/0616		return 1;
1991/0705		}
1990/0617		}
1992/0812		pprint("suicide: invalid address 0x%lux in sys call pc=0x%lux\n", addr, userpc());
1992/0616		return 0; } void validaddr(ulong addr, ulong len, int write) { if(!okaddr(addr, len, write)) pexit("Suicide", 0);
1991/0705		}
1990/0227		/* * &s[0] is known to be a valid address. */ void*
1991/0705		vmemchr(void *s, int c, int n)
1990/0227		{ int m; char *t; ulong a; a = (ulong)s; m = BY2PG - (a & (BY2PG-1));
1991/0705		if(m < n){ t = vmemchr(s, c, m);
1990/0227		if(t) return t; if(!(a & KZERO)) validaddr(a+m, 1, 0);
1991/0705		return vmemchr((void*)(a+m), c, n-m);
1990/0227		}
1991/0705		/* * All in one page */ return memchr(s, c, n);
1990/0227		}
1991/0705		Segment* seg(Proc *p, ulong addr, int dolock)
1990/0227		{
1991/0705		Segment **s, **et, *n;
1990/0227
1991/0606		et = &p->seg[NSEG];
1991/0705		for(s = p->seg; s < et; s++)
1991/0927		if(n = *s){ if(addr >= n->base && addr < n->top) { if(dolock == 0) return n; qlock(&n->lk); if(addr >= n->base && addr < n->top) return n; qunlock(&n->lk); }
1991/0705		}
1991/0611
1990/0227		return 0; }